Device for casting of metal

ABSTRACT

A device for continuous or semi-continuous casting of metal comprising a mould having a number of mould elements ( 1, 2 ) which together form a mould adapted for receiving a liquid metal ( 6 ), a mould supporting structure ( 30, 31 ) surrounding the mould and mechanically supporting it, and an induction coil ( 20 ) arranged close to the mould for reducing the contact pressure between the melt and the mould. At least one of the mould elements is divided into at least a first ( 1   a,    2   a ) and a second ( 1   b,    2   b ) part arranged so that they are electrically insulated from each other, the first mould element part being arranged before the second mould element part relative to the casting direction and said induction coil is arranged close to the first mould element part ( 1   a,    2   a ).

TECHNICAL FIELD

The present invention relates to a device for continuous orsemi-continuous casting of metal, comprising a mould with a number ofmould elements which together form a casting mould adapted to receive aliquid metal, a mould supporting structure that surrounds the mould andmechanically supports it, and an induction coil arranged adjacent to themould to reduce the contact pressure between the melt and the mould. Thedevice is used to advantage in continuous casting of metal or metalalloys to form an elongated casting, a so-called cast strand.

BACKGROUND ART

In continuous or semi-continuous casting of metals and metal alloys, ahot melt is supplied to a chilled mould intended for continuous casting,that is, a mould that is open in both ends in the casting direction. Themould is normally water-cooled and surrounded and supported by asupporting structure. Usually, the supporting structure comprisessupporting beams or supporting plates provided with inner cavities orchannels for a coolant, such as water. The melt is supplied to themould, whereby the metal solidifies and a cast strand is formed when itpasses through the casting mould. When the cast strand passes out of themould, it comprises a solidified self-supporting shell around aremaining melt.

To prevent the cast strand from adhering to the mould wall, anoscillatory motion is imparted to the mould. To further prevent thesolidified self-supporting shell from adhering to the mould wall, alubricant is usually supplied to the upper surface of the melt in themould. Through the oscillations, so-called oscillation marks arise onthe surface of the cast strand. If the solidified surface layer shouldadhere to the mould, this manifests itself as considerable surfacedefects and in certain cases as a ripping of the solidified surfacelayer.

One known way of preventing the occurrence of oscillation marks on thecast strand is to make use of electromagnetic casting (EMC). Duringelectromagnetic casting, an ac field generates forces acting to separatethe melt and the mould and thus reduce the contact pressure between themelt and the mould. Because of these separating forces, the risk ofadhesion and the risk of oscillation marks are reduced. Further,improved conditions for lubricating the mould are achieved. In this way,the surface fineness of the finished casting may be improved.

The ac field that is needed during electromagnetic casting is obtainedfrom a coil arranged at the upper end of the mould. This coil may haveone or more phases. Preferably, a high-frequency alternating magneticfield is applied. Usually, the inductive coil is fed with an alternatingcurrent with a fundamental frequency of 50 Hz or more. For slabs, thefrequency is preferably in the interval of 50–1000 Hz, but higherfrequencies are feasible. The compressive forces that are generated bythe high-frequency magnetic field reduce the pressure between the mouldwall and the melt, whereby the conditions for lubrication areconsiderably improved. The surface quality of the cast strand isimproved and the casting speed may be increased without jeopardizing thesurface quality. A disadvantage that has occurred in connection withelectromagnetic casting is that the induced power losses become veryhigh.

A typical mould for casting of large castings comprises four plates madeof copper or a copper alloy which together form a casting mould. Theseplates are supported by a supporting structure of plates and/or beams.To reduce the inductive power losses, it is known to use stainless steelin this supporting structure, but the power losses are stillsignificant.

Swedish patent document No. 512691 discloses a device for casting ofmetal, where the power induced in the supporting beams and supportingplates of the mould is reduced, which in turn results in the totalinduced power losses being reduced. The disclosed device comprises amould, an induction coil arranged at the upper end of the mould, and amould supporting structure to mechanically support the mould. The mouldcomprises a number of mould elements, which are separated by means ofpartitions, each of which comprises an electrically insulating barrier.Each mould element is associated with a corresponding mechanicallysupporting mould supporting structure part and an electric conductorwith an electrical conductivity that is higher than the electricalconductivity of the supporting structure.

The electric conductor is arranged close to the mould supportingstructure part on that side of the mould supporting structure part thatfaces away from the mould. The barriers in the partitions break thecurrent paths for the electric currents that are induced in the mould bythe magnetic field, whereby the penetration of the melt by the magneticfield is facilitated and the induction power losses in the mould areminimized. The electric conductor provides an advantageous return pathfor the current that is induced by the high-frequency magnetic field,such that the induced power losses are minimized in the supportingstructure. Admittedly, this mould arrangement reduces the induced powerlosses, but still the induced power losses are too high.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a device forcontinuous or semi-continuous casting of metal which, by usingelectromagnetic casting, improves the conditions for the initialsolidification of the cast strand and which exhibits low induced powerlosses.

This object is achieved with the device described in the introductorypart of the description, which is characterized in that at least one ofthe mould elements is divided into at least a first and a second part,arranged so as to be electrically insulated from each other, whereby thefirst mould element part is arranged before the second mould elementpart relative to the casting direction and said inductive coil isarranged close to the first mould element part.

An analysis of the currents that are induced by the coil has shown thatthe induced current on the outside of the mould is concentrated at aband right in front of the coil, whereas the induced current on theinside of the mould is essentially evenly distributed along the heightof the entire mould. This even distribution of the current in thevertical direction on the inside of the mould results in the magneticfield in the space formed between the mould and the melt beingsubstantially constant from the lower edge of the mould to the surfaceof the melt, the so-called meniscus. Thus, the electromagnetic pressurebecomes essentially constant over the entire mould height. Such adistribution of the current becomes inefficient for two reasons: first,because only the electromagnetic pressure in the region nearest belowthe meniscus can be utilized, and, second, because the electromagneticpressure is inversely proportional to the propagation of the current inthe vertical direction. This implies that the higher the mould is, thesmaller will be the electromagnetic pressure. Currently, the trend is toincrease the length of the mould, which means that the effect of themagnetic field is reduced.

By dividing the mould, vertically, into at least two parts which areelectrically insulated from each other, and arranging the inductive coilclose to the one of the mould parts, the propagation of the inducedcurrent in the vertical direction on the inside of the mould can belimited to a region around the meniscus, hence reducing the inducedpower losses. An improvement of the efficiency is attained even whendividing one or a few of the mould elements. One advantage of thepresent invention is that the electromagnetic pressure remains the sameirrespective of the length of the mould.

According to a preferred embodiment of the invention, the first andsecond mould element parts are arranged spaced from each other, so thata gap is formed between them, and that the gap is arranged substantiallyacross the casting direction. The mould element is divided by a gappreventing the induced currents from reaching the lower part of themould element. The gap is advantageously filled with some insulatingmaterial, but it may also be filled with air.

According to another preferred embodiment of the invention, the gap isarranged at a distance from the lower edge of the coil that is smallerthan 15 cm. With this arrangement, and provided that the coil isarranged essentially on a level with the meniscus, a concentratedmagnetic field, and hence high inwardly directed forces, are exerted onthe melt where it is really needed, that is, in the vicinity of themeniscus.

According to one embodiment of the invention, the divided mould elementconstitutes at least one side in the casting mould, and the gap isarranged such that the position of the gap in relation to the coilvaries along the side of the mould. Instead of having a purelyhorizontal gap, the position of the gap may be allowed to vary in thevertical direction. In this way, it is possible, at least to a certainextent, to control the distribution of the electromagnetic pressure onthe melt along the sides of the mould.

According to one embodiment of the invention, the gap has an irregularshape, in a section across its longitudinal axis, to bring about alocking in the lateral direction of the first and the second mouldelement parts against each other. According to a further embodiment ofthe invention, the gap is arranged, in a section across its longitudinalaxis, to be inclined in relation to a plane across the castingdirection. One of the tasks of the mould is to retain the cast strandand hence the mould elements are sometimes subjected to largeoutwardly-directed forces. To prevent the mould element parts fromsliding apart, the gap is advantageously formed, in the cross sectionacross the thickness of the mould, with an oblique or irregular shape,or formed with slots to lock the mould element parts to each other.

According to a further embodiment of the invention, the mould comprisesfour mould elements in the form of mould plates, two of the mould platesconstituting the long sides of the casting mould and the other two mouldplates constituting the short sides of the casting mould, and at leastthe two mould plates that constitute the long sides of the casting mouldare divided into said first and second mould element parts. Preferably,the two mould plates that constitute the short sides of the castingmould each consist of one coherent part. Dividing only the long sides ofthe mould, while leaving the two short sides undivided, has theadvantage that the mould manages the above-mentioned outwardly-directedforces in a better way when two sides are undivided while at the sametime the improvement of the efficiency becomes almost as high as whenall the sides are divided.

According to an additional embodiment of the invention, the mouldsupporting structure comprises a number of mould supporting memberswhich are each arranged to support one of said mould elements, wherebythe mould supporting member that is arranged to support said dividedmould element is divided, in the-same way as the mould element, into afirst and a second mould supporting part electrically insulated fromeach other, the first mould supporting part being arranged to supportthe first mould element part and the second mould supporting part beingarranged to support the second mould element part. The currents that areinduced by the coil are induced not only in the mould elements but alsoin the surrounding supporting structure. To further reduce the inducedpower losses, also the surrounding supporting structure is divided inthe same way as the mould.

According to another embodiment of the invention, the mould supportingstructure comprises a number of mould supporting parts, each onearranged to support any of said mould element parts, whereby the mouldsupporting part that is arranged to support said divided mould elementpart consists of a coherent part that supports both the upper and thelower mould element part. By dividing only the mould element and not themould supporting member that supports the mould element parts, a bettermechanical stability in the mould is obtained.

According to a further embodiment of the invention, said divided mouldelement is divided into at least three parts, the third mould elementpart being arranged before the first mould element part relative to thecasting direction and electrically insulated from the first mouldelement part. The third and first mould element parts are advantageouslyarranged spaced from each other so as to form a gap between them and sothat the gap is arranged substantially transversely of the castingdirection. By introducing a third division in the upper part of themould, the propagation of the induced current in the vertical directionis limited further to the region around the meniscus. This second gapmay be given varying shapes, described above for the first gap.

According to an additional embodiment of the invention, the mouldelements are arranged electrically insulated from each other and anelectric conductor with a higher electrical conductivity than theelectrical conductivity of the supporting structure is arranged on thatside of the mould supporting structure that faces away from the mould.To reduce the power losses further, the divided mould according to theinvention may be provided with an electric conductor arranged on theoutside of the supporting structure. The electric conductor constitutesan advantageous return path for the current and hence minimizes theinduced power losses in the supporting structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be explained by means of differentembodiments, described as examples, and with reference to theaccompanying drawings.

FIG. 1 is a section along the casting direction through a device forcontinuous casting according to a first embodiment of the invention.

FIG. 2 is a section A—A across the casting direction through the deviceof FIG. 1.

FIG. 3 is a section along the casting direction through a device forcontinuous casting according to a second embodiment of the invention.

FIGS. 4 a–4 b show alternative embodiments of a gap between mouldelement parts in a cross section across the thickness of the mould.

FIG. 5 shows an alternative embodiment of the gap, wherein the gap isarranged so that the position of the gap in relation to the upper end ofthe mould varies along the side of the mould.

FIG. 6 is a section along the casting direction through a device forcontinuous casting according to a third embodiment of the invention.

FIGS. 7 and 8 show further embodiments of a device for casting accordingto the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

A mould for continuous casting is open at both ends in the castingdirection and comprises means for ensuring that the formed cast strandcontinuously leaves the mould. The mould is continuously supplied with aflow of hot molten metal.

While the melt passes through the mould, it is cooled and solidifies atleast partly, whereby a cast strand is formed.

FIGS. 1 and 2 show a device for continuous casting of metal. The devicecomprises a mould, which comprises a number of mould elements 1, 2, 3and 4 which together form a casting mould arranged to receive a liquidmetal 6. The mould elements 1–4 are plate-formed and will be designatedmould plates in the following. A mould plate is usually made of copperor a copper-based alloy, which may be provided with a coating on theinner surface which faces the melt during operation. The mould plates 1and 2 also face each other and constitute short sides in the castingmould. Further, the mould plates exhibit a high thermal and electricalconductivity. The cooling plates are provided cooling channels (notshown).

Each one of the mould plates 1 and 2, which constitute long sides in thecasting mould, is divided into two parts, a first mould element part 1a, 2 a, and a second mould element part 1 b, 2 b. The first mouldelement part 1 a, 2 a is arranged before the second mould element part 1b, 2 b, as viewed relative to the casting direction. The first mouldelement parts 1 a, 2 a are arranged to be electrically insulated fromthe second mould element parts 1 b, 2 b. The first mould element parts 1a, 2 a are preferably arranged on a level with the upper surface of themelt, the meniscus 22.

The first mould element part 1 a is arranged at a distance from andabove the second mould element part 1 b, in such a way that a gap 8 a isformed between the mould element parts. In a corresponding way, thefirst mould element part 2 a is arranged at a distance from and abovethe second mould element part 2 b, thus forming a gap 8 b therebetween.The gaps 8 a, 8 b are arranged substantially transversely of the castingdirection. During continuous casting, the casting direction ispreferably vertical, which means that the gap is preferably arrangedhorizontally. The gaps 8 a, 8 b are preferably filled with someinsulating material, for example glass fibre-reinforced epoxy, but thegap may also be an air gap.

The mould plates 3, 4, which constitute short sides in the castingmould, may either be divided into a first and a second mould elementpart, in the same way as the mould plates 1, 2, or each one of the mouldplates 3, 4 may consist of one single coherent part. Usually, theheight/width ratio for the short sides is such that a division of themould plates 3, 4 only provides a marginal improvement of theefficiency. From the point of view of strength, it is therefore betteronly to divide the mould plates 1, 2 that constitute the long sides.

The mould is surrounded by a mould supporting structure thatmechanically supports the mould. The mould supporting structurecomprises a number of mould supporting members 10, 11, 12, 13 in theform of mould supporting plates, which are each arranged to support oneof the mould plates 1, 2, 3, 4. The mould supporting plates 10, 11, 12,13 are usually made of steel girders and comprise internal channels orcavities for a flowing coolant such as water. The mould plates 1, 2, 3,4, with the corresponding mould supporting plates 10, 11, 12, 13, arearranged to be electrically insulated from one another with the aid ofpartitions 15, 16, 17, 18. The mould supporting plates 10, 11, 12, 13are preferably made from stainless steel to minimize the induced powerlosses.

The mould plates 1, 2, 3, 4 and the mould supporting plates 10, 11, 12,13 are surrounded by an induction coil 20. The coil 20 is preferablyarranged at the upper end of the mould on a level with the meniscus 22.The coil 20 is arranged so as to generate and apply a high-frequencyalternating magnetic field acting on the melt 6 in the upper end of themould during casting. The magnetic field, in turn, generates compressiveforces on the melt which thereby reduces the pressure between the mouldplates 1, 2, 3, 4 and the melt 6. For casting of slabs, the frequency ofthe magnetic field is preferably in the interval of 50–1000 Hz, buthigher frequencies are feasible. The coil 20 is usually a single-phasecoil and has an extent in the casting direction that is about 15 cm. Toobtain improved efficiency, the gaps 8 a, 8 b should be arranged at adistance h from the lower edge of the coil which is smaller than 15 cm.To further concentrate the electromagnetic field and hence increase theefficiency, it is advantageous to arrange the coils at a distance h fromthe lower edge of the coil which is smaller than 10 cm.

As will be clear from FIG. 1, the mould supporting plates 10, 11 arearranged on the outside of the mould plates in such a way as to extendalong both the first 1 a, 1 b and the second 2 a, 2 b mould elementpart. The mould supporting plates 10, 11 make electrical contact withthe first mould element parts 1 a, 2 a. The mould supporting plates 10,11 and the second mould element parts 1 b, 2 b are arranged to beelectrically insulated from each other. Thus, the mould plates 1, 2 aredivided, whereas the supporting plates are undivided to provide bettermechanical stability.

FIG. 3 shows an alternative embodiment of a device for continuouscasting of metal. It should be noted that components having acorresponding structure and function are provided with the samereference numerals in all the embodiments. The device in FIG. 3 differsfrom the device in FIG. 1 in that the mould supporting plates 30, 31,which are arranged to support the divided mould plates 1, 2, aredivided, in the same way as the mould plates 1, 2, into a first mouldsupporting part 30 a, 31 a and a second mould supporting part 30 b, 31 bwhich are electrically insulated from each other. The first mouldsupporting part 30 a, 31 a is arranged to support the first mouldelement part 1 a, 2 a and the second mould supporting part 30 b, 31 b isarranged to support the second mould element part 1 b, 2 b.

The first mould supporting part 30 a is arranged along the entire mouldelement part la and the mould supporting part 30 b is arranged along theentire length of the mould element part 1 b. The mould supporting part30 a and the mould element part 1 a together form a first unit and themould supporting part 30 b and the mould element part 1 b form a secondunit, which units are arranged spaced from each other so as to form agap 35 between them. The gap 35 is arranged substantially transverselyof the casting direction. The mould element parts 2 a, 2 b and the mouldsupporting parts 31 a, 31 b are arranged in a corresponding way.

In the preceding embodiments, the gaps 8 a, 8 b, 35 were essentiallyhorizontal in a section across their own longitudinal axes. To improvethe mechanical strength, the gap may, for example, be formed as shown inFIGS. 4 a and 4 b. In FIG. 4 a, a gap 40 that is inclined in relation tothe horizontal plane, is shown. Such an inclined gap absorbsoutwardly-directed forces from the melt that act in a separating way onthe mould element parts. FIG. 4 b shows a gap 41 that is provided with aslot to lock the first mould element part 2 a and the correspondingmould supporting part 31 a to the second mould element part 2 b and thecorresponding mould supporting part 31 b.

As shown in FIG. 5, it is also possible to allow the position of the gapin the vertical direction to vary along the side of the mould. FIG. 5shows a gap 43 between the mould element parts 2 a, 2 b, wherein theposition of the gap along the side of the mould, in the z-direction inthe figure, varies in relation to the lower side of the mould. In thisway, it is possible to vary the distribution of the electromagneticpressure on the melt along the side of the mould.

Calculations of the power have been carried out by means of a 3D FEMprogram, for solution of electromagnetic field problems, on a deviceintended for continuous casting with the strand dimension 2000×250 mmand with a mould height of 700 mm, according to the embodiment of theinvention shown in FIG. 3. The calculations show that, at the sameelectromagnetic pressure on the melt at the meniscus, the total activepower is reduced by about 44% compared with an undivided mould. At thesame time, the reactive power is reduced by about 47%. For a device forcasting according to the embodiment shown in FIG. 1, the correspondingfigures are 25% and 28% for total active and reactive power,respectively.

To further limit the propagation of the induced current in the verticaldirection to the region around the meniscus, the mould plates may bedivided into more than two parts. FIG. 6 shows an embodiment, in whichat least two of the mould plates 50, 51 are each divided into threemould element parts, a first mould element part 50 a, 51 a, a secondmould element part 50 b, 51 b and a third mould element part 50 c, 51 c.The third mould element part 50 c, 51 c is arranged before the firstmould element part 50 a, 51 a, viewed relative to the casting direction.The mould element parts 50 a, 50 b, 50 c are arranged spaced from andelectrically insulated from one another so as to form two gaps 55, 56.

Thus, the mould plate 50 comprises two gaps 55, 56 arrangedsubstantially transversely of the casting direction. In case of avertical casting direction, the gaps are substantially horizontallyarranged. The first gap 55 is arranged above the meniscus 22 and thesecond gap 56 is arranged below the meniscus 22. In this way, thepropagation of the induced current is limited both upwardly anddownwardly to the region around the meniscus 22. In the embodiment shownin FIG. 6, the mould supporting plates 10, 11 extend along all the threemould element parts 50 a, 50 b, 50 c, 51 a, 51 b, 51 c. FIG. 7 shows analternative embodiment in which the mould supporting plates 60 aredivided into three mould supporting parts 60 a, 60 b, 60 c. The mouldsupporting parts 60 a, 60 b, 60 c form, together with the mould elementparts 50 a, 50 b, 50 c, units which, as viewed in the casting direction,are arranged one after the other and spaced from each other so as toform gaps 65, 66 between them.

A casting device according to the invention may advantageously beprovided with an electric conductor arranged close to the mouldsupporting structure. Electric conductors 70, 71, with a higherelectrical conductivity than the electrical conductivity of thesupporting structure, are arranged close to the first mould supportingparts 30 a, 31 a, on that side which faces away from the mould. Theelectric conductors 70, 71 provide advantageous return paths for thecurrent that is induced by the high-frequency magnetic field so that theinduced power losses are minimized in the supporting structure.

The invention is not limited to the embodiments shown, but may be variedand modified within the scope of the following claims. For example, theinductance coil may be replaced by several inductance coils.

1. A device for continuous or semi-continuous casting of metal,comprising a mold with a number of mold elements, which together form acasting mold adapted to receive a liquid metal, a mold supportingstructure which surrounds the mold and mechanically supports it, and aninduction coil arranged close to the mold to reduce the contact pressurebetween the melt and the mold, wherein at least one of the mold elementsis divided into at least a first and a second part arranged so as to beelectrically insulated from one another, whereby the first mold elementpart is arranged before the second mold element part relative to thecasting direction and said induction coil is arranged close to the firstmold element part, wherein the first and the second mold element partsare arranged spaced from each other so as to form a gap between them andthat the gap is arranged substantially transversely of the castingdirection, and wherein the gap is arranged at a distance from the loweredge of the coil that is smaller than 15 cm.
 2. The device for castingof metal according to claim 1, wherein the gap is filled with aninsulating material.
 3. The device for casting of metal according toclaim 1, wherein said divided mold element constitutes at least one sideof the casting mold and said gap is arranged so that the position of thegap in relation to the coil varies along the side of the mold.
 4. Thedevice for casting of metal according to claim 1, wherein the gap, in asection across its longitudinal axis, has an irregular shape to achievelocking in the lateral direction of the first and second mold elementparts to each other.
 5. The device for casting of metal according toclaim 1, wherein the gap, in a section across its longitudinal axis, isarranged so as to be inclined in relation to a plane transversely of thecasting direction.
 6. The device for casting of metal according to claim1, wherein the mold comprises four mold elements in the form of moldplates, whereby two of the mold plates constitute the long sides of thecasting mold, and the other two mold plates constitute the short sidesof the casting mold, and that at least the two mold plates thatconstitute the long sides of the casting mold are divided into saidfirst and second mould element parts.
 7. The device for casting of metalaccording to claim 6, wherein each one of the two mold plates thatconstitute the short sides of the casting mold consists of a coherentpart.
 8. The device for casting of metal according to claim 1, whereinthe mold supporting structure comprises a number of mould supportingmembers, each one being arranged to support any of said mold elements,wherein the mold supporting member that is arranged to support saiddivided mold element is divided in the same way as the mold element intoa first and a second mold supporting part, electrically insulated fromeach other, whereby the first mold supporting part is arranged tosupport the first mold element part and the second mold supporting partis arranged to support the second mold element part.
 9. The device forcasting of metal according to claim 1, wherein the mold supportingstructure comprises a number of mold supporting parts, each one beingarranged to support any of said mold elements parts, wherein the moldsupporting part that is arranged to support said divided mold elementconsists of a coherent part supporting both the upper and the lower moldelement parts.
 10. The device for casting of metal according to claim 1,wherein said divided mold element is divided into at least three parts,whereby the third mold element part is arranged before the first moldelement part relative to the casting direction and electricallyinsulated from the first mold element part.
 11. The device for castingof metal according to claim 10, wherein the third and the first moldelement parts are arranged spaced from each other so as to form a gapbetween them and that the gap is arranged substantially transversely ofthe casting direction.
 12. The device for casting of metal according toclaim 1, wherein the mold supporting structure comprises a number ofmould supporting parts, each one being arranged to support any of saidmold elements parts, wherein the mould elements are arranged to beelectrically insulated from one another and that an electric conductorwith a higher electrical conductivity than the electrical conductivityof the supporting structure is arranged on that side of the moldsupporting structure that faces away from the mold.
 13. A device forcontinuous or semi-continuous casting of metal, comprising a mold with anumber of mold elements, which together form a casting mold adapted toreceive a liquid metal, a mold supporting structure which surrounds themold and mechanically supports it, and an induction coil arranged closeto the mold to reduce the contact pressure between the melt and themold, wherein at least one of the mold elements is divided into at leasta first and a second part arranged so as to be electrically insulatedfrom one another, whereby the first mold element part is arranged beforethe second mold element part relative to the casting direction and saidinduction coil is arranged close to the first mold element part, whereinthe first and the second mold element parts are arranged spaced fromeach other so as to form a gap between them and that the gap is arrangedsubstantially transversely of the casting direction, and wherein thegap, in a section across its longitudinal axis, is arranged so as to beinclined in relation to a plane transversely of the casting direction.14. The device for casting of metal according to claim 13, wherein thegap is filled with an insulating material.
 15. The device for casting ofmetal according to claim 13, wherein the gap is arranged at a distancefrom the lower edge of the coil that is smaller than 15 cm.
 16. Thedevice for casting of metal according to claim 13, wherein said dividedmold element constitutes at least one side of the casting mold and saidgap is arranged so that the position of the gap in relation to the coilvaries along the side of the mold.
 17. The device for casting of metalaccording to claim 13, wherein the gap, in a section across itslongitudinal axis, has an irregular shape to achieve locking in thelateral direction of the first and second mold element parts to eachother.
 18. The device for casting of metal according to claim 13,wherein the mold comprises four mold elements in the form of moldplates, whereby two of the mold plates constitute the long sides of thecasting mold, and the other two mold plates constitute the short sidesof the casting mold, and that at least the two mold plates thatconstitute the long sides of the casting mold are divided into saidfirst and second mould element parts.
 19. The device for casting ofmetal according to claim 18, wherein each one of the two mold platesthat constitute the short sides of the casting mold consists of acoherent part.
 20. The device for casting of metal according to claim13, wherein the mold supporting structure comprises a number of mouldsupporting members, each one being arranged to support any of said moldelements, wherein the mold supporting member that is arranged to supportsaid divided mold element is divided in the same way as the mold elementinto a first and a second mold supporting part, electrically insulatedfrom each other, whereby the first mold supporting part is arranged tosupport the first mold element part and the second mold supporting partis arranged to support the second mold element part.
 21. The device forcasting of metal according to claim 13, wherein the mold supportingstructure comprises a number of mold supporting parts, each one beingarranged to support any of said mold elements parts, wherein the moldsupporting part that is arranged to support said divided mold elementconsists of a coherent part supporting both the upper and the lower moldelement parts.
 22. The device for casting of metal according to claim13, wherein said divided mold element is divided into at least threeparts, whereby the third mold element part is arranged before the firstmold element part relative to the casting direction and electricallyinsulated from the first mold element part.
 23. The device for castingof metal according to claim 22, wherein the third and the first moldelement parts are arranged spaced from each other so as to form a gapbetween them and that the gap is arranged substantially transversely ofthe casting direction.
 24. The device for casting of metal according toclaim 13, wherein the mold supporting structure comprises a number ofmould supporting parts, each one being arranged to support any of saidmold elements parts, wherein the mould elements are arranged to beelectrically insulated from one another and that an electric conductorwith a higher electrical conductivity than the electrical conductivityof the supporting structure is arranged on that side of the moldsupporting structure that faces away from the mold.